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With the ongoing climate change affecting the ocean, there is a need to understand and predict the future distributions of marine species in order to assess the sustainability of marine ecosystem. In this study, remotely-sensed satellite oceanographic data together with Indian mackerel (Rastrelliger kanagurta) fishery dataset were used to predict potential fishing grounds in the Exclusive Economic Zone (EEZ) of Peninsular Malaysia using boosted regression trees (BRT) model. The model was developed using three years (2008–2010) fish catch data and environmental variables of chlorophyll-a (chl-a), sea surface temperature (SST) and sea surface height (SSH). Result indicated that potential fishing grounds were closely associated with SSH, followed by SST and chl-a. The performance of the BRT model indicated acceptable fishing grounds prediction accuracy (AUC value of 0.749). Seasonal variability in fishing grounds was related to favorable environmental conditions of SSH (1.1–1.3 m), SST (29–32 °C) and chl-a (0.3–0.6 mg/m3). The projection of increases in SST due to climate change according to IPCC-AR5-RCPs was observed to influence the spatial and temporal distributions R. kanagurta. Increased temperature at 1.80 °C resulted in high potential catch areas for R. kanagurta in the EEZ. Meanwhile, elevated temperature at 2.60 °C and 3.30 °C showed decreased in potential catch areas for R. kanagurta in the EEZ. Most of the future fishing grounds area were projected to decline, and it was observed to shift outside the EEZ off South China Sea. Hence, by understanding these relationships, this analysis identifies where strategies can be adapted to face the ecological impacts under changing environmental conditions.

Increasing human-induced climate issues, such as water pollution, have triggered rapid physiochemical changes, especially in coastal regions. These changes have directly impacted aquatic animals that live near coastal areas, such as bivalves and crustaceans (e.g., clams, crabs), as well as those that live in the lower areas of the habitat (i.e., sediment). Heavy metal pollution (e.g., mercury) is one of the most concerning physiochemical changes in these areas. The effects of heavy metals on coastal environments and organisms can be substantial, in spite of restoration efforts. Thus, more studies are needed to analyze the current situation of the impacts of climate-change-related issues on heavy metal concentrations in coastal areas. In this paper, we provide a scientometrics analysis of the interactions between climate change and heavy metal concentrations in coastal regions around the world. Scientometrics is the quantitative analysis of the available literature, with a focus on research patterns, using continuous and systematic methods. Our results showed that there was a total of 7922 related studies from 1979 to 2021. Heavy metal contamination, ecological quality status and ocean acidification are among the most influential keywords in this field. We concluded that among climate change issues, heavy metals are becoming a popular topic within research associated with climate change.

Carbon dioxide (CO2) concentrations at the ocean surface are in approximate equilibrium with the atmosphere. Consequently, the amount of CO2 dissolved in oceans increases with increasing atmospheric CO2 concentrations. Through ocean acidification, increase uptake of CO2 at the ocean surface lowers the ocean pH level. The availability of dissolved carbonate and bicarbonate primarily caused by CO2 uptake from the atmosphere also changes. Periodically or permanently elevated CO2 concentrations can become a general stress factor in aquatic environments. Excess CO2 can affect the surrounding ocean life, i.e., disturbing growth performance, reproduction, changes in skeletal and otolith development, and fish behavior. Studies on the effects of ocean acidification on fish species have recently received attention. This condition can lead to severe problems if atmospheric CO2 concentrations continue to rise. Therefore, management intervention and decisive action on excessive CO2 emission are necessary to overcome this situation. The information discussed in this review can be utilized as reference in understanding the effects of ocean acidification on marine ecosystem and associated fishes.

Climate warming and low pH environment are known to negatively impact all levels of aquatic organism from cellular to organism and population levels. For ammonotelic freshwater species, any abiotic factor fluctuation will cause disturbance to the fish, specifically at the gills which act as a multifunctional organ to support all biological processes. Therefore, this study was designed to investigate the effect of temperature (28 vs. 32 degrees C) and pH (7.0 vs. 5.0) stress on the gill plasticity of Hoven's carp after 20 days of continuous exposure. The results demonstrated that high temperature and low pH caused severe changes on the primary and secondary lamellae as well as the cells within lamellae. An increasing trend of the proportion available for gas exchange was noticed at high temperature in both pH exposures, which resulted from a reduction of the primary lamellae width with elongated and thinner secondary lamellae compared to fishes at ambient temperature. Following exposure to high temperature and acidic pH, Hoven's carp experienced gill modifications including aneurysm, oedema, hypertrophy, curling of secondary lamellae, epithelial lifting, hyperplasia and lamellae fusion. These modifications are indicators of the coping mechanism of Hoven's carp to the changing environment in order to survive.

This study reports the discovery of the exclusive predation of sea turtle hatchlings by several juvenile blacktip reef sharks (Carcharhinus melanopterus) in Chagar Hutang bay on Redang Island, Malaysia, in the South China Sea. Three dead specimens of C. melanopterus were retrieved from ghost nets, and the entire digestive tracts of these sharks solely contained the partially digested bodies of sea turtle hatchlings, with no evidence of the remains of any other prey. Thus, juvenile C. melanopterus may opportunistically feed primarily on turtle hatchlings during times when hatchling abundance is high.

The growth pattern, diet and reproductive biology of the clownfish Amphiprion ocellaris collected from waters of Pulau Tioman were investigated. The length-weight relationship showed an isometric growth pattern (b = 3) in A. ocellaris. The stomach contents mainly consisted of zooplankton and algae, which showed that the fish is omnivorous and was confirmed by trophic level analysis (2.98 ± 0.29). Fecundity of A. ocellaris ranged from 23-1518 with mean egg count of 582 ± 478, and has positive relationships with body length, body weight, eviscerated weight and ovary weight. The gonads were also described and examined histologically. The ovaries showed 4 stages of maturity, displaying different colours for each stage. The different developments of oocytes were also found in each stage of maturity. The males and non-breeders comprised of both testicular and ovarian tissues. In the males, the testicular tissues were more prominent in the ovotestes, whereas in non-breeders the primary oocytes were more prominent. Absence of testicular tissue in ovaries of females showed that the fish is a protandrous hermaphrodite and sex change may not be reversible. Similar observations have been reported in A. ocellaris of other countries and other Amphiprion species indicating that Amphiprion species show consistency in their reproduction strategy throughout their range. Keywords: Reproductive biology, Growth pattern, Stomach content, Amphiprion ocellaris, Protandrous hermaphrodite

In this study we analyzed the effects of water temperature and diet on the growth properties and gastric emptying period of juvenile Malabar blood snapper (Lutjanus malabaricus) over a 30 day experimental period. Fish were collected from a local hatchery of Pulau Ketam, Selangor, Malaysia and immediately transferred to flow-through sea water system and subjected to four different temperatures (22, 26, 30, and 34 °C) and two diets (formulated pellet and shrimp). Body weight gain, food consumption, food conversion ratio, food consumption efficiency, specific growth rate, relative growth rate, daily growth rate, and gastric emptying time were significantly influenced by temperature and diet (P

An integrated experiment was performed on juvenile Malabar blood snapper (Lutjanus malabaricus) to investigate the effect of temperature and diet in their pepsin activities in relation with digestive somatic index (IDS) and relative gut length (RGL). One hundred twenty L. malabaricus juvenile (13–15 cm) were equally distributed among four exposed temperature treatments (22, 26, 30 and 34 °C) representing their seasonal range and to account for end of century predicted temperatures, and two diets as commercial pellet and natural shrimp. After 7 days of acclimation period fish were reared for 30 days in twenty four 400 l glass aquaria at a stocking density of 5 fish tank−1. All treatments were three replications. The result showed that, IDS and RGL gradually decreased with increasing temperature up to 30 °C and again increase at 34 °C. And the values were also higher in pellet feeding fish than shrimp feeding fish at all the temperatures. Alternatively, in pepsin activity, an increased activity was seen between 26 °C to 30 °C and this activity was significantly higher than the 22 °C and 34 °C (P

The influences of live and formulated feeds on growth performances, muscle fibers morphometry and muscle growth-related gene expression of Malaysian mahseer, Tor tambroides larvae were evaluated in indoor nursery rearing system. Quadruplicate groups of T. tambroides larvae (0.07 ± 0.01 g, mean ± SE) were stocked in sixteen aquaria (60 × 30 × 30 cm), randomly arranged in four dietary treatments viz. larvae fed artemia (LA), moina (LM), daphnia (LD) and formulated feed (FF) with stocking density of 34 larvae per aquarium. The larvae were fed to visually near satiation in two equal feedings per day, seven days per week for 75 days. The growth-related parameters (mean weight gain and specific growth rate) were significantly highest in treatment FF, followed by treatment LA and the lowest in treatment LD or LM. Histological observation and muscle morphometric analysis revealed that mosaic hyperplasia was observed after 50 days of the feeding trial. Hypertrophic (diameter class 50 = 40 > d ≤ 50 μm and class 60 = d > 50 μm), but not hyperplastic (diameter class ≤10 μm), muscle fibers frequencies were significantly highest in larvae fed FF compared to those fed live feeds. The entire open reading frame cDNA sequences of two important growth-related genes, myogenin and MyoD, were successfully amplified and cloned from T. tambroides larvae. The nucleotide sequences alignment using CLUSTAL W in BioEdit program of both MyoD and myogenin genes showed the sign of existence of isoforms and highly conserved with other cyprinid fishes. Real-time PCR data demonstrated that myogenin and MyoD gene expressions were significantly upregulated in larvae fed FF. The results of the present experiment concluded that the nursery rearing of T. tambroides larvae with formulated feed showed augmented muscle growth and upregulated growth-related gene expression than feeding live feeds.

Hybrid grouper (Epinephelus fuscoguttatus [TG] × E. lanceolatus [GG]) juveniles were evaluated in terms of their blood hematology and biochemical levels after 60 days of exposure to different temperatures (22 °C, 26 °C, 30 °C, and 34 °C) in triplicate (20 fish/tank; body weight 200 ± 15 g; length 22.5 ± 1 cm). The fish were fed daily with commercial pellets (42% protein, 9% ash, and 11% lipid) or shrimp (42% protein, 9% ash, and 11% lipid). Results showed that the blood hematologic parameters of the fish fed with shrimp at 26 °C were significantly better than those at other temperatures. The lowest stress level measured in terms of glucose (26 ± 10 mg dL−1) and cortisol concentrations (0.5 ± 0.1 ng mL−1) after 60 days of the experiment were observed in the fish fed with shrimp at 26 °C compared with those fed with other diets and at other temperatures. Overall, the TGGG hybrid showed the highest red blood cell and total protein counts in fish fed with a shrimp diet at 26 °C, which were healthful and less stressful conditions. Thus, the health of TGGG hybrid fed with shrimp was better than that of fish fed with other diets and at other temperatures. These findings would be useful for further studies on the management of the TGGG hybrid to increase production. Keywords: Aquaculture, Hematology, Cortisol, Grouper, Temperature

The effects of temperatures (22, 26, 30 and 34 °C) and diets (commercial pellet and shrimp) on the growth properties and gastric emptying time (GET) of the tiger grouper × giant grouper (TGGG) hybrid were analyzed over a 30 day experimental period under controlled laboratory conditions. Food consumption (FC), food conversion rate (FCR), specific growth rate (SGR) and GET were significantly influenced by temperature and diet type. The highest mean SGR (1.00% BM day−1, p 0.05) were observed between any of the groups at 22 and 34 °C fed on either the shrimp or the pellet diet. The lowest statistically significant (p

Temperature- and prey-specific gastrointestinal evacuation times and gastrointestinal emptying rates were estimated for Lutjanus malabaricus under laboratory condition by using X-radiography and serial slaughtering techniques. Fish were collected from Pulau Ketam, Selangor, Peninsular Malaysia and subjected to four different experimental temperatures (22 °C, 26 °C, 30 °C and 34 °C) and two different types of feeding (pellet diet or shrimp (Acetes sp.)). The results of X-radiography and serial slaughtering showed that the initial voidance of faecal matter began 4–8 h after feeding at all temperatures. The fastest gut emptying time and rates were seen in the 30 °C group fed with shrimp diet (16 h), where the proportion of meal remaining in the stomach decreased from 100% to less than 8% after 12 h of starvation. A significant delay in gut emptying was observed in the 22 °C group fed with formulated pellet diet (28 h). The best performance was observed at 30 °C group fed with shrimp diet. L. malabaricus fish mass (W, g) was also incorporated into a modified square root model, which fitted the wet mass gut evacuation data obtained by the serial slaughtering method regardless of temperature and prey type (adjusted r2 > 0.99). The results of this study suggested that L. malabaricus should be cultured in 30 °C and fed with shrimp diet to optimize its commercial production and condition.

White spot syndrome virus (WSSV) is a devastating, infectious virus affecting farming tiger shrimp (Penaeus monodon). In efforts to limit trans-boundary movement of this pathogen and reduce the economic and socioeconomic impact of disease in shrimp culture, there is considerable scope for more effective use of DNA-based methods of pathogen detection. To assess the prevalence of the WSSV, broods, nauplii and post-larvae (PL) samples were collected from nine shrimp hatcheries located in the southeast and southwest regions of Bangladesh during the period from February 2008 to May 2014 and subjected to screening for WSSV by polymerase chain reaction (PCR) technique. The prevalence of WSSV during the 7-year period ranged from 48.15 to 62.99 %, 12.88 to 31.55 % and 4.03 to 8.89 % in broodstocks, nauplii and post-larvae, respectively. Out of a total of 5489 brood samples analyzed during the 7 years, 2,977 were found to be PCR positive for WSSV giving an overall prevalence of 54.24 %. The overall rates of PCR positive were 19.52 % for nauplii and 6.25 % for PL. The rates of infection in the nauplii and PL were much less than that observed in the broodstocks as the nauplii and PL samples were collected from broods found to be negative for WSSV by PCR. A follow-up study showed successful culture in about 87 % of the shrimp farms stocked with the PL that were PCR negative for WSSV. This study confirmed that PCR is an effective diagnostic tool for the screening of broodstocks before being used for spawning in the hatchery, to prevent vertical transmission of WSSV from parents to larvae. However, to avail the advantage of PCR screening for a risk-free crop, sources of potential horizontal contaminations should also be controlled.

X-radiography can be used to estimate gastric emptying time, which is valuable in calculating food consumption and growth rates in fishes. The movement of food through the alimentary tract (gastric motility) of banded archerfish, Toxotes jaculatrix (Pallas, 1767), was observed in the laboratory under natural conditions of temperature (27 °C) and salinity (28) using X-radiography, with barium sulphate (BaSO4) as an inert food marker. Nutrient absorption along the alimentary tract (expressed as relative percentage absorption gradient) was calculated using the apparent digestibility coefficient (ADC) based on ash contents of adjacent samples. We found that initial voiding of fecal matter began 6-12 hrs after feeding commenced, and that alimentary tracts were completely emptied within 96 hrs. Considerable proportions of all macronutrients were absorbed in the short region (anterior intestine/pyloric caeca), but active absorption continued along the longer middle and posterior intestinal segments. The macro- nutrient in wild-fed T. jaculatrix differed (51% protein, 63% lipid, 20% carbohydrate, and 40% energy) from that of laboratory-fed fish (75% protein, 96% lipid, 50% carbohydrate, and 87% energy), due to the fact that the proximate contents of macronutriet in the wild-fed fish were unknown, while the diet of the laboratory-fed fish was initially known. Gut passage times in T. jaculatrix was longer than those reported in various temperate carnivorous fishes, which is surprising given the higher temperatures in the tropics, however, all previous studies were performed on cultured fish fed commercial pellets and therefore direct comparisons are not possible. Slow gut passage may depend on the types of food ingested (e.g., high chitinous mealworm) that correlated to lower food consumption. Our results generally indicated that T. jaculatrix is opportunistic feeders regardless of the macronutrient content of the prey.

Increasing carbon dioxide (CO2) in the ocean are predicted to affect vital physiological functions and possibly reduce growth of marine fish. Yet, studies on the impacts on marine fish with the increasing CO2 is still limited. Therefore, this study aimed to explore the elevated CO2 effect on the growth and welfare (condition factor, blood parameters, stress analysis, gill histology) of newly developed commercially important marine fish, tiger grouper (Epinephelus fuscoguttatus) × giant grouper (E. lanceolatus) hybrid or TGGG. TGGG juveniles were exposed for 120 days in a laboratory condition of CO2 groups: 390 μatm (control-current CO2), 610 μatm (moderate) and 1010 μatm (high) consistent with projections for CO2 concentrations in the ocean over the next 50–100 years. The experiments were done in triplicate (20 fish/tank; N = 180, total length = 20.0 ± 0.5 cm, weight = 94.0 ± 3.0 g). Results showed that the lowest specific growth rate (SGR) (0.65 ± 0.05% day−1) and condition factor (1.12 ± 0.01) were observed in high CO2. Unfavourable blood haematological and biochemical parameters were observed in high CO2 group. The highest stress level measured by glucose (102 ± 8 mg dL−1) and cortisol concentration (1.0 ± 0.1 ng mL−1) were also observed in the high CO2. Gill lesions were histologically observed in high CO2 treatment. The results suggested that high CO2 negatively affected the growth and welfare of TGGG. Outputs of this study would offers a simple tool to evaluate the potential risk of elevated CO2 to an important commercial marine grouper.

Reproductive biology of the introduced sailfin cat fish Pterygoplichthys pardalis in the Langat River of peninsular Malaysia was studied. Fish samples were collected monthly from Langat River during March 2003 - June 2004. The sex ratio observed for P. pardalis was female-biased with 1: 2. Gonadal maturity stage is achieved at 12.5 cm standard length (SL) for males and 13.0 cm SL for females. This species appeared to have continuous spawning that peaked when water levels were high between September and January. Egg sizes were found to reach as large as 3.3 mm in dia in the ovary; suggesting that they spawn in batches. Fecundity varied from 1297 to 18791 numbers per brood, proportional to individual size. Data obtained from this study indicate that the introduced sailfin cat fish has successfully colonised in Langat River in Malaysia.